The trucks with 16 tonnes of food aid and six tonnes of water purification tablets had been held up on the Turkish side for three days to sort out customs' formalities.

"They've crossed the border and they are now on the Iraqi side. They're waiting there for clearance from the customs, which shouldn't take long," said Michael Bociurkiw, spokesman for the United Nations Children's Fund in Silopi, the last Turkish town before the border.

He said the trucks will held to Dohuk, a Kurdish-controlled city in the north which has been off limits to Baghdad since the last Gulf war.

UNICEF officials have said the humanitarian situation in northern Iraq, where some 200,000 displaced people are living, is critical and quickly getting worse.

The trucks were sent in under the oil-for-food program reactivated last week.

A second convoy of some 40 trucks carrying aid valued at four million dollars has also been held up. The spokesman said UNICEF had initially hoped it would enter Iraq as early as Wednesday but had been delayed indefinitely.

SPACE.WIRE